Genome-Wide Identification of the Soybean Phosphofructokinase Gene Family and Functional Characterization of GmPFK6 in Salt Tolerance Regulation

Phosphofructokinase (PFK), a core metabolic enzyme conserved across all organisms, plays a pivotal role in plant growth and development as well as in the regulation of responses to abiotic stresses. While the PFK gene family has been characterized in a variety of plant species and a partial identification in soybean has been reported recently, the complete repertoire and the functional roles of this gene family in soybean remain to be fully elucidated, with inconsistencies in gene number observed across different studies. In this study, we further performed a systematic genome-wide screening of soybean and identified a total of 27 GmPFK family members. Phylogenetic tree analysis further classified these members into three distinct subfamilies. Conserved structure analysis revealed that all GmPFKs contain the PFK domain (PF00365). Real-time quantitative PCR (qRT-PCR) analysis demonstrated that the GmPFK6 gene exhibited a significant upregulation of expression under salt stress. Furthermore, the GmPFK6 gene was cloned and introduced into soybean hairy roots. The results demonstrated that under salt stress, the root length and fresh weight of hairy roots from the control lines were significantly greater than those from the transgenic lines. In addition, under salt stress, the superoxide dismutase (SOD) activity in the control lines was significantly higher than that in the transgenic lines, while the malondialdehyde (MDA) content in the transgenic lines was significantly lower than that in the control lines.